Pneumatic test-hole drill.



A. M. BAIRD.-

PNEUMATIC TEST HOLE DRILL. APPLICATION FILED FEB. 3. I916- Patented Apr. 17, 1917.

an srarns orrron ARCHIE M. BAIRD, 0F 'IOPEKA, KANSAS, ASSIGNOR T0 BAIRD PNEUMATIC TOOIi COM- PANY, OF TOPEKA, KANSAS, A CORPORATION OF KANSAS. y

PNEUMATIC TEST-HOLE DRILL.

Specification of Letters Patent.

Patented Apr. 17, 1917.

Application filed February 3, 1916. Serial No. 76,018.

To all whom itmag concern.

Be it known that I, ARCHIE M. BAIRD, a citizen of the United States, residing at T0- peka, in the county of Shawnee and State of Kansas, have invented certain new and useful Improvements in Pneumatic Test- Hole Drills, of which the following is a specification.

Owing to the great number, there being several hundred, of stay-bolts in each boiler,

it is quite out of question to drill the staybolts for test-holes by hand, as by a breastdrill; and it is the usual shop practice to use portable power drills for this purpose, usually electric motors or reciprocating engines furnishing the power. While these are in a measure portable, they are quite heavy, weighing in the neighborhood of fifty pounds and upward; and it is also customarily necessary to use some auxiliary devices, such as the well known old man, and feeding devices, to aid the workman in the manipulation of the tool.

It is the primary object of my invention to produce a power drill suitable for drilling test-holes that is of extreme lightness, so that it can be easily handled by the workman without the aid of any auxiliary de vice. It is a further object to produce a test-hole drill that is of extreme simplicity and that has a small number of simple parts. It is a further object to produce a pneumatic test-hole drill that is light, strong, durable, simple, and efficient, and inexpensive as well; and enables shops to make their own repairs.

My invention comprises a certain association of drill spindle with a rotary pneumatic motor, and it also comprises the parts, improvements and combinations relating thereto, as hereinafter described and claimed.

In the drawings accompanying and forming part of this specification and in the description of the drawings, I have shown my invention in its preferred form and what I deem to be the best mode of applying the principles thereof; and it is to be understood that, within the scope of the appended claim, I contemplate changes in size, form, proportions, and materials, the transposition of parts, and the substitution of equivalent members, Without departing from the spirit of my invention.

Figure 1 is a vertical sectional elevation on the plane indicated by the line ale-m in Fig. 2 of a test-hole drill made in accord ance with my invention, the handle being removed and the extreme lower end being broken away. Fig. 2 is a sectional plan View on a plane indicated by the line y 1 in Fig. 1. Fig. 3 is a view of the piston blade, removed. Fig. 4 is a side view of part of the motor.

Similar reference characters indicate similar parts throughout the several views.

The cylinder casing 6 is formed with a tangentially extending boss 7 and inlet port 8; and the boss is internally screw-threaded, as indicated at 9. The cylinder is also formed with a number of exhaust ports 11.

The cylinder heads 12 and 13, secured to the casing by means of cap screws 14, are formedwith countersinks 15, 15, which receive the opposite ends of the rotary piston 16. The piston is eccentrically disposed with relation to the cylinder and bears against one side of the cylinder, as shown diametrically opposed slots coextensive as to length with thepiston blade and cylinder. The piston blade 18'is mounted in the piston through the slots and is of such width as to permit rotation of the piston, and its width is obviously less than the diameter of the cylinder. A groove 19 is formed in each outer edge of the blade, and a pack- .ing strip 20 is fitted therein. A number of holes 21 are drilled from the side of the blade to which the motive fluid is applied, which holes extend into the bottom of the groove; their purpose being to admit the motive fluid under the packing strips to force the strips outwardly against the wall of the cylinder to make a perfect seal. A groove 22 is formed in the piston in front of each hole for'the purpose of admitting.

threaded nipple 25 onto which the drill spindle or chuck 26 is screwed up tight against the shoulder.

The upper end of the piston is also formed with a stem 80 extending into the upper cylinder head 12, and ball thrust bearings 31 are provided between the end of the piston and the head, to reduce the friction caused by the thrust stress between the rotating piston, spindle, and bit, and the casing, while the drill is pressed to its work.

The upper end of the upper head is formed with a screw-threaded socket 32 to receive the handle.

The operation of the drill will readily be understood from the foregoing description.

A drill made in about the proportions shown, with a two-by-three-inch cylinder, weighs about three pounds, and it develops ample power when supplied with air at approximately one hundred pounds pressure to drive a three-sixteenths bit, rapidly and efiiciently, in the drilling of test-holes. Its extreme light weight makes it convenient and not burdensome to operate.

Although the primary purpose of this invention is the drilling of test-holes, I do not in any manner limit its use to that particular purpose. It will also be understood that while I have referred to the part 26 as a spindle, it may also as well be called a chuck, as, in effect, the piston and its integral parts form the spindle. And this spindle or chuck 26 may be unscrewed and removed if it should be desired to use some other type of chuck with the tool.

I am aware that heretofore drills have been designed with rotary pneumatic motors including some of the elements of the combinations hereinafter claimed, and including all of such elements in other combinations. But my invention relates to the simplifying Copies of this patent may be obtained for of the motor element so as to render it of extreme lightness and greater efficiency with no sacrifice of the qualities of strength and durability.

WVhat I claim is:

A pneumatic test hole drill comprising in combination, a cylindrical casing, a head secured to one end thereof, said head having three relatively concentric eccentric counten sinks, a head secured to the other end of said casing and having an eccentric countersink therein and an opening therethrough concentrio with said countersink, a hollow cylindrical rotor eccentrically arranged within said casing with one end portion seated within the largest countersink in said first-named head. and the other end portion seated within the countersink of the second-named head, a stem formed on said first-named end of said rotor and projecting into the smallest countersink of saidfirst-named head, said stem being surrounded by a thrust bearing arranged within the next to the largest countersink in said first-named'head, a shouldered stem formed on said second-named end of said rotor and projecting through the opening in said second-named head, a single sliding piston arranged transversely of said rotor, the outer edges of said piston being formed longitudinally with radial grooves and with ports leading into .the bottom of said grooves from that side of the blade which receives the motive fluid, and radially reciprocating packing strips mounted in said grooves, said piston being formed with a groove in front of each of said ports.

ARCHIE M. BAIRD.

five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

